The solution I use is for the child processes to feed array updates back to the master process, which applies them to the array. This has worked for me because the worker processes I have needed thus far have always had fully-defined tasks at the moment they are forked — the only communication needed is to report their results back to the master process.

I have used this technique to maintain Tk GUI responsiveness while issuing network queries in the background, but the data to scrape is known when the process forks and the child only needs to parse a reply and pass the "important bits" back up.